Time is an important element in the daily lives of most individuals. Many meetings and other events require that the individual arrive in a timely manner Many individuals wear an electronic wristwatch or carry an electronic timepiece in their pocket or purse. Other individuals choose to rely on other portable electronic devices such as laptop computers, portable tablets and portable phones to provide the correct time. Many individuals utilize an electronic calendar in various types of electronic devices to remind them of meetings and events. Reliance on such devices has become an important part of the daily lives of many individuals, both in a business and personal setting.
Many kitchen appliances, test and measurement equipment, such as signal generators, and most portable electronic devices, such as cellphones, clocks, radios, and digital watches, keep time using quartz crystal controlled oscillators. A crystal oscillator is an electronic oscillator circuit that uses the mechanical resonance of a vibrating crystal of piezoelectric material to create an electrical signal with a very precise frequency. Digital logic is used to count the cycles of the signal and to provide a time display in the form of hours, minutes and seconds. The most common type of piezoelectric resonator used is the quartz crystal, so oscillator circuits incorporating them are often referred to as crystal oscillators. Because of their compact size and because they are relatively inexpensive, quartz crystal is generally recognized as the most widely employed system of timekeeping in the world today.
Quartz crystal oscillators are generally accurate to approximately ±15 seconds per month. Environmental factors such as temperature, humidity, pressure and vibration, as well as battery voltage and age of the quartz crystal, typically influence the accuracy of a device's timekeeping. Methods and systems such as thermal compensation have been employed in an attempt to compensate for the environmental factors affecting the accuracy of quartz crystal oscillator timekeeping devices. Other types of materials such as ceramics may be used in some instances to replace quartz but those materials may also have their accuracy affected by various environmental factors.
Several techniques already exist to synchronize devices to a common time base, such as use of the Network Time Protocol (NTP) to synchronize to atomic clocks over the Internet, or use of a Global Positioning System (GPS) receiver to synchronize to the time signal transmitted by each GPS satellite. Typically, these techniques require Internet connectivity or GPS satellite reception, and so will not work under some circumstances. For example, a device that is outdoors may have access to GPS time, while a device that is indoors may only have access to the NTP system.
Because of a desire to have time synchronization among a variety of electronic devices in relative close network proximity it would be desirable to have a method and system which allows for accurate time synchronization among a group of electronic devices under varying conditions.